<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="https://cdn.bootcss.com/vue/2.6.10/vue.js"></script>
</head>
<body>
    <div id="app">
        <input type="text" v-model="keyword"><button @click="handleAdd">添加</button>
        <h4>历史记录</h4>
        <button v-for="item of historyWords">{{item}}</button>
       <!-- 超出减少办法2
     <button v-for="item of historyWords.slice(0,4)">{{item}}</button> -->
    </div>
    <script>
        new Vue({
            el:"#app",
            data(){
                return{
                    msg:"hello world",
                    keyword:"",
                    // historyWord的长度为8
                    historyWords:["你的名字","王妃"]
                }
            },
            methods:{
                handleAdd(){
                    
                    if(!this.historyWords.includes(this.keyword)){
                          this.historyWords.unshift(this.keyword)
                       
                    }
                    if(this.historyWords.length>5){
                        this.historyWords.pop()
                    }
                  
                }
            }

        })
    
    </script>
</body>
</html>